The present invention relates to a work holding jig for use in a mounted state to a vice.
According to the prior art, for clamping works of special shapes, e.g. a round bar, by means of a vice, there are separately produced specially-machined mouthpieces suitable for clamping such special-shape works, and only the mouthpiece portion is replaced.
Also, according to the prior art, when a thin work is to be clamped, a leveling stand is mounted on a vice and the work is put thereon and clamped. It is troublesome to separately produce the foregoing mouthpieces of special shapes, and it is also very troublesome and takes time to remove the mouthpiece already mounted and attach another mouthpiece. Besides, at every replacement of a mouthpiece a mounting error is apt to occur, often resulting in poor accuracy.
The operation using a leveling stand for clamping a thin work has also been very troublesome. For setting a thin work to an optimum height using a leveling stand, it has been necessary to perform a height adjusting operation with high accuracy. In the case of a rather thick work it has not been necessary to adjust the height so accurately, but as the work thickness becomes smaller, it is required to hold a large portion of the work by a mouthpiece and clamped completely, thus it has been necessary to make an accurate height adjustment to hold the work. In an actual operation, therefore, it is necessary to prepare several hundred kinds of leveling stands and select and use one having a suitable thickness. However, providing several hundred kinds of leveling stands troublesome in point of production and management, and the selection of a suitable one from among several hundred kinds is inefficient.
According to the prior art, moreover, when it is impossible to provide several hundred kinds of leveling stands, there is adopted a method wherein two or more are picked out from among a small number of kinds and select the most suitable one out of various combinations. In this case, however, it is troublesome and takes time to find out the most suitable combination.
In the case of using a leveling stand, moreover, the work positioning operation involves difficulty because the leveling stand moves. Besides, chip is apt to enter below the leveling stand, so it is necessary to make cleaning at every loading or unloading of a work, thus resulting in markedly deteriorated working efficiency.